SCALES OF BUDS AND BULBS 



107 



(Fig. 161) ; also the scarlet sage of gardens and the 

 flaming poinsettia of greenhouses. 



220. The scales of buds are special kinds of bracts. In 

 some cases each scale represents an entire leaf; in others, 

 it represents a petiole or stipule. In the expanding pear, 

 maple, lilac, hickory, and 

 horse-chestnut buds, note the 

 gradation from dry scales to 

 green leaf -like bodies. When 

 the winter scales fall by the 

 pushing out of the young 

 shoot, scars are left : these 

 scars form "rings," which 

 mark the annual growths. 

 See Chap. VII. The scales 

 of bulbs are also special 

 kinds of leaves or bracts. 

 In some cases they are merely 

 protective bodies ; in others 

 they are storeJiouses . We 

 have found (45) that the 

 presence of scales or bracts is one means of distinguish 

 ing underground stems from roots. 



161. In the bougaiuvillea three gaudily 

 colored bracts surround each clus- 

 ter of three small flowers. 



Review. — What are considered to be the fundamental or type 

 forms from which the parts of plants are derived? How do the forms 

 of plants interest us? What is morphology? What is meant by trans- 

 formation and modification as used by the morphologist ? What is 

 meant by homologous parts ? Analogous parts? Tell how one may 

 determine the morphology of any i>art. What is a cladophyllum ? 

 Pliyllodium ? Show a specimen of one or the other, or both 

 (canned asparagus can always be had in the market). What is 

 the morphology of most thorns? Explain the thorns of hawthorn. 

 What are bristles, prickles, and hairs? Why do spines and bristles 

 exist! Explain what a bract is. A bud-scale. A bulb-scale. 



